This invention relates to the manufacture of plastic objects by extrusion, and more particularly to apparatus for the continuous cooling of elongated elements of plastic material at the end of a production line, of the type comprising an elongated enclosure having endwalls adapted to allow the passage of the elongated element and capable of retaining a liquid contained in the enclosure when the elongated element is in place.
In installations designed for the continuous extrusion of elongated elements such as plastic tubes or insulating sheaths for copper conductors, for example, elongated cooling vats, generally of sheet metal, are placed just next to the extrusion head. The endwalls of such vats include apertures through which the plastic element enters and leaves the vat. When there is no need for calibrating devices, it suffices for the apertures to match the cross-section of the plastic element in order to prevent major leakage of water between the element and the edge of the aperture. These vats have hitherto been no more than water-tight enclosures of welded sheet metal, open at the top and with apertures in each of the endwalls. Such enclosures are provided with the necessary connections for the water supply and for drainage, as well as with fixtures for mounting rollers or guide-rolls placed in the bottom of the vat to support the elongated element when it is of a relatively large diameter.
However, the electronic control of extrusion installations now makes it possible to pass very quickly and easily from production of an element of one size to production of an element of a different size. Now, with vats of conventional design, every time a line is started up for manufacturing an element of a given size, e.g., a wire or cable, this element must be passed through the entry and exit apertures of the vat, the vat itself having been completely changed in many cases in order for the apertures to be adapted to the new diameter. It was this situation which prompted research into a new vat design.
It is therefore the object of this invention to provide improved cooling apparatus which, while relatively simple, can easily be adapted to the diameters or cross-sections of various elongated elements in order to simplify the starting-up of a production line when there is a change in dimensions.